Onion Recipe

Prepare and slice onions

Preheat oven to 400°F (200°C). Peel the onions and cut off the stem ends. Slice each onion in half through the root, then place cut-side down and slice each half into 1/4-inch (6 mm) half-moons. Keep the slices roughly even so they cook uniformly.

Sear to begin caramelization

Heat a large ovenproof skillet over medium heat. Add the olive oil and butter and swirl until foam subsides and butter is melted. Add the sliced onions in an even layer and cook, stirring every 2–3 minutes, until they soften and begin to turn translucent (about 6–8 minutes).

Add seasonings and cook slowly

Sprinkle the sugar, kosher salt, and black pepper over the onions and stir to coat. Continue to cook on medium-low, stirring frequently, until the onions turn deeply golden and richly caramelized, about 20–25 minutes. If the pan begins to stick or the onions dry out, add 1–2 tablespoons water or vegetable broth and scrape up browned bits from the bottom.

Finish in the oven

Stir in the balsamic vinegar and the remaining 1–2 tablespoons water or broth. Transfer the skillet to the preheated oven and roast for 8–10 minutes to concentrate flavor and encourage further browning, stirring once halfway through. Remove from oven when edges are deeply browned and onions are soft and jammy.

Add herbs and adjust seasoning

Return skillet to the stove over low heat. Stir in the fresh thyme leaves, taste, and adjust seasoning with additional salt, pepper, or a splash more balsamic vinegar if desired. Let rest 2–3 minutes before serving so flavors meld.

If serving on bread, toast baguette slices until crisp. Spoon warm caramelized onions over the toast and scatter crumbled goat cheese or grated Parmesan and chopped parsley on top. Serve immediately as a side for dinner, a topping for grilled meats, or as part of a composed salad or tart.